/*
 * OutputDocument.java July 2006
 *
 * Copyright (C) 2006, Niall Gallagher <niallg@users.sf.net>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

package wx.xml.simpleframework.xml.stream;

import wx.xml.stax.api.stream.Location;

/**
 * The <code>OutputDocument</code> object is used to represent the
 * root of an XML document. This does not actually represent anything
 * that will be written to the generated document. It is used as a
 * way to create the root document element. Once the root element has
 * been created it can be committed by using this object.
 *
 * @author Niall Gallagher
 */
class OutputDocument implements OutputNode {

    /**
     * Represents a dummy output node map for the attributes.
     */
    private OutputNodeMap table;

    /**
     * Represents the writer that is used to create the element.
     */
    private NodeWriter writer;

    /**
     * This is the output stack used by the node writer object.
     */
    private OutputStack stack;

    /**
     * This represents the namespace reference used by this.
     */
    private String reference;

    /**
     * This is the comment that is to be written for the node.
     */
    private String comment;

    /**
     * Represents the value that has been set on this document.
     */
    private String value;

    /**
     * This is the name of this output document node instance.
     */
    private String name;

    /**
     * This is the output mode of this output document object.
     */
    private Mode mode;

    /**
     * Constructor for the <code>OutputDocument</code> object. This
     * is used to create an empty output node object that can be
     * used to create a root element for the generated document.
     *
     * @param writer this is the node writer to write the node to
     * @param stack  this is the stack that contains the open nodes
     */
    public OutputDocument(NodeWriter writer, OutputStack stack) {
        this.table = new OutputNodeMap(this);
        this.mode = Mode.INHERIT;
        this.writer = writer;
        this.stack = stack;
    }

    /**
     * The default for the <code>OutputDocument</code> is null as it
     * does not require a namespace. A null prefix is always used by
     * the document as it represents a virtual node that does not
     * exist and will not form any part of the resulting XML.
     *
     * @return this returns a null prefix for the output document
     */
    public String getPrefix() {
        return null;
    }

    /**
     * The default for the <code>OutputDocument</code> is null as it
     * does not require a namespace. A null prefix is always used by
     * the document as it represents a virtual node that does not
     * exist and will not form any part of the resulting XML.
     *
     * @param inherit if there is no explicit prefix then inherit
     * @return this returns a null prefix for the output document
     */
    public String getPrefix(boolean inherit) {
        return null;
    }

    /**
     * This is used to acquire the reference that has been set on
     * this output node. Typically this should be null as this node
     * does not represent anything that actually exists. However
     * if a namespace reference is set it can be acquired.
     *
     * @return this returns the namespace reference for this node
     */
    @Override
    public String getReference() {
        return reference;
    }

    /**
     * This is used to set the namespace reference for the document.
     * Setting a reference for the document node has no real effect
     * as the document node is virtual and is not written to the
     * resulting XML document that is generated.
     *
     * @param reference this is the namespace reference added
     */
    @Override
    public void setReference(String reference) {
        this.reference = reference;
    }

    /**
     * This returns the <code>NamespaceMap</code> for the document.
     * The namespace map for the document must be null as this will
     * signify the end of the resolution process for a prefix if
     * given a namespace reference.
     *
     * @return this will return a null namespace map object
     */
    @Override
    public NamespaceMap getNamespaces() {
        return null;
    }

    /**
     * This is used to acquire the <code>Node</code> that is the
     * parent of this node. This will return the node that is
     * the direct parent of this node and allows for siblings to
     * make use of nodes with their parents if required.
     *
     * @return this will always return null for this output
     */
    @Override
    public OutputNode getParent() {
        return null;
    }

    /**
     * To signify that this is the document element this method will
     * return null. Any object with a handle on an output node that
     * has been created can check the name to determine its type.
     *
     * @return this returns null for the name of the node
     */
    public String getName() {
        return null;
    }

    /**
     * This is used to change the name of an output node. This will
     * only affect the name of the node if the node has not yet been
     * committed. If the node is committed then this will not be
     * reflected in the resulting XML generated.
     *
     * @param name this is the name to change the node to
     */
    @Override
    public void setName(String name) {
        this.name = name;
    }

    /**
     * This returns the value that has been set for this document.
     * The value returned is essentially a dummy value as this node
     * is never written to the resulting XML document.
     *
     * @return the value that has been set with this document
     */
    public String getValue() throws Exception {
        return value;
    }

    /**
     * This is used to set a text value to the element. This effect
     * of adding this to the document node will not change what
     * is actually written to the generated XML document.
     *
     * @param value this is the text value to add to this element
     */
    @Override
    public void setValue(String value) {
        this.value = value;
    }

    /**
     * This is used to get the text comment for the element. This can
     * be null if no comment has been set. If no comment is set on
     * the node then no comment will be written to the resulting XML.
     *
     * @return this is the comment associated with this element
     */
    @Override
    public String getComment() {
        return comment;
    }

    /**
     * This is used to set a text comment to the element. This will
     * be written just before the actual element is written. Only a
     * single comment can be set for each output node written.
     *
     * @param comment this is the comment to set on the node
     */
    @Override
    public void setComment(String comment) {
        this.comment = comment;
    }

    /**
     * This method is used to determine if this node is the root
     * node for the XML document. The root node is the first node
     * in the document and has no sibling nodes. This will return
     * true although the document node is not strictly the root.
     *
     * @return returns true although this is not really a root
     */
    @Override
    public boolean isRoot() {
        return true;
    }

    /**
     * The <code>Mode</code> is used to indicate the output mode
     * of this node. Three modes are possible, each determines
     * how a value, if specified, is written to the resulting XML
     * document. This is determined by the <code>setData</code>
     * method which will set the output to be CDATA or escaped,
     * if neither is specified the mode is inherited.
     *
     * @return this returns the mode of this output node object
     */
    @Override
    public Mode getMode() {
        return mode;
    }

    /**
     * This is used to set the output mode of this node to either
     * be CDATA, escaped, or inherited. If the mode is set to data
     * then any value specified will be written in a CDATA block,
     * if this is set to escaped values are escaped. If however
     * this method is set to inherited then the mode is inherited
     * from the parent node.
     *
     * @param mode this is the output mode to set the node to
     */
    @Override
    public void setMode(Mode mode) {
        this.mode = mode;
    }

    /**
     * This method is used for convenience to add an attribute node
     * to the attribute <code>NodeMap</code>. The attribute added
     * can be removed from the element by using the node map.
     *
     * @param name  this is the name of the attribute to be added
     * @param value this is the value of the node to be added
     * @return this returns the node that has just been added
     */
    @Override
    public OutputNode setAttribute(String name, String value) {
        return table.put(name, value);
    }

    /**
     * This returns a <code>NodeMap</code> which can be used to add
     * nodes to this node. The node map returned by this is a dummy
     * map, as this output node is never written to the XML document.
     *
     * @return returns the node map used to manipulate attributes
     */
    @Override
    public NodeMap<OutputNode> getAttributes() {
        return table;
    }

    /**
     * This is used to set the output mode of this node to either
     * be CDATA or escaped. If this is set to true the any value
     * specified will be written in a CDATA block, if this is set
     * to false the values is escaped. If however this method is
     * never invoked then the mode is inherited from the parent.
     *
     * @param data if true the value is written as a CDATA block
     */
    @Override
    public void setData(boolean data) {
        if (data) {
            mode = Mode.DATA;
        } else {
            mode = Mode.ESCAPE;
        }
    }

    /**
     * This is used to create a child element within the element that
     * this object represents. When a new child is created with this
     * method then the previous child is committed to the document.
     * The created <code>OutputNode</code> object can be used to add
     * attributes to the child element as well as other elements.
     *
     * @param name this is the name of the child element to create
     */
    public OutputNode getChild(String name) throws Exception {
        return writer.writeElement(this, name);
    }

    /**
     * This is used to remove any uncommitted changes. Removal of an
     * output node can only be done if it has no siblings and has
     * not yet been committed. If the node is committed then this
     * will throw an exception to indicate that it cannot be removed.
     *
     * @throws Exception thrown if the node cannot be removed
     */
    public void remove() throws Exception {
        if (stack.isEmpty()) {
            throw new NodeException("No root node");
        }
        stack.bottom().remove();
    }

    /**
     * This will commit this element and any uncommitted elements
     * elements that are decendents of this node. For instance if
     * any child or grand child remains open under this element
     * then those elements will be closed before this is closed.
     *
     * @throws Exception this is thrown if there is an I/O error
     *                   or if a root element has not yet been created
     */
    @Override
    public void commit() throws Exception {
        if (stack.isEmpty()) {
            throw new NodeException("No root node");
        }
        stack.bottom().commit();
    }

    /**
     * This is used to determine whether this node has been committed.
     * This will return true if no root element has been created or
     * if the root element for the document has already been commited.
     *
     * @return true if the node is committed or has not been created
     */
    @Override
    public boolean isCommitted() {
        return stack.isEmpty();
    }

    @Override
    public Location getLocation() {
        return null;
    }

    @Override
    public String debugDescription() {
        return null;
    }
}
